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The Energy Blog is where all topics relating to The Energy Revolution are presented. Increasingly, expensive oil, coal and global warming are causing an energy revolution by requiring fossil fuels to be supplemented by alternative energy sources and by requiring changes in lifestyle. Please contact me with your comments and questions. Further Information about me can be found HERE.

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September 11, 2005

Sunball Rooftop Solar Concentrator

Green and Gold Energy, Australia is developing the SunBall™ rooftop solar system. Incorporating a high efficiency (>30%) solar energy concentrator, an automatic dawn to dusk internal 2 axis tracking system and solar cells that are cooled by radiation to a low operating temperature. Extensive testing is being done to ensure 25+ years of life, high reliability and ease of installation.

"The company's goal is to reduce the delivered cost of rooftop generated photovoltaic (PV) kWhs to below that available from the grid. Solar PV then becomes a sensible financial and logical choice for domestic and commercial electricity users."

Green and Gold have completed development of a 0.4 meter diameter SunBall™ , with 42 Wp output and are proceeding with development of a 1 m2 unit with a 1.3 kWp output. The 1 m2 SunBall™ is expected to be available early in 2006 for a price of AUS$1,613 (US$1250.) It is expected that units for export will be available by July 2006. The 0.4 meter SunBall™ suitable for battery charging, will be available at the same time.

The SunBall™ uses a non reflective coated optical acrylic Fresnel lens to capture the light from an area 500 times that of the solar cell and focus it onto a triple junction solar cell. Each hexagonal shaped Fresnel lens (segment) is about 5.5 inches (13.9 cm) long on each side with the solar cell located about 7.9 inches (200 mm) beneath the lens. Each segment of the units is identical, so there is no scaling of this component required between the 7 segment 0.4 m unit and the 19 segment 1 m2 unit.

The Sunball uses Spectrolab 35-38% efficiency triple junction solar cells similar to those used in the Mars rovers. The cell is attached to a large diameter heat sink which transfers the heat to the aluminum outer shell of the SunBall™ maintaining a temperature 10 oC above ambient, a lower operating temperature than is achieved in solar panels.

Using "Max kWh Tracking"™ the the sun is continually tracked to ensure the best power generation. This is done by continuously searching the sky to obtain the maximum PV current. The internal microprocessor can also command an increasing spiral sky scan to find and lock onto the sun or brightest sky spot if the sun is obscured by clouds. This search capability means the SunBall™ can be quickly installed on flat or sloping roofs without regard to polar alignment, date, time, etc. The SunBall™'s 2 axis tracker is mounted internally (to reduce environmental degradation) and is designed to handle loads 5 times greater than the SunBall™ will ever encounter.

Their website shows a map of the US with cost of electricity per kW for various regions. This shows a cost per kWh of $0.072 to $0.084 in the sunniest southwestern states and $0.126 to $0.168 in the upper Midwest and northeast for four 1 m2 , 1.3 Wp SunBall's at $6000 25 year life and no rebates. (the second site listed gives the cost as $6,400 plus inverter).

This seems like a very straightforeward, simple, sensible design for a home rooftop unit and other moderately sized installations. Seems much less complex than theSunflowerand it can be installed on a sloped roof. Let the best unit win!